/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.messaging.simp.config;

import org.springframework.lang.Nullable;
import org.springframework.messaging.support.ChannelInterceptor;
import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

/**
 * A registration class for customizing the configuration for a
 * {@link org.springframework.messaging.MessageChannel}.
 *
 * @author Rossen Stoyanchev
 * @since 4.0
 */
public class ChannelRegistration {

    private final List<ChannelInterceptor> interceptors = new ArrayList<>();
    @Nullable
    private TaskExecutorRegistration registration;

    /**
     * Configure the thread pool backing this message channel.
     */
    public TaskExecutorRegistration taskExecutor() {
        return taskExecutor(null);
    }

    /**
     * Configure the thread pool backing this message channel using a custom
     * ThreadPoolTaskExecutor.
     *
     * @param taskExecutor the executor to use (or {@code null} for a default executor)
     */
    public TaskExecutorRegistration taskExecutor(@Nullable ThreadPoolTaskExecutor taskExecutor) {
        if (this.registration == null) {
            this.registration = (taskExecutor != null ? new TaskExecutorRegistration(taskExecutor) :
                    new TaskExecutorRegistration());
        }
        return this.registration;
    }

    /**
     * Configure the given interceptors for this message channel,
     * adding them to the channel's current list of interceptors.
     *
     * @since 4.3.12
     */
    public ChannelRegistration interceptors(ChannelInterceptor... interceptors) {
        this.interceptors.addAll(Arrays.asList(interceptors));
        return this;
    }

    protected boolean hasTaskExecutor() {
        return (this.registration != null);
    }

    protected boolean hasInterceptors() {
        return !this.interceptors.isEmpty();
    }

    protected List<ChannelInterceptor> getInterceptors() {
        return this.interceptors;
    }

    /**
     * Configure interceptors for the message channel.
     *
     * @deprecated as of 4.3.12, in favor of {@link #interceptors(ChannelInterceptor...)}
     */
    @Deprecated
    public ChannelRegistration setInterceptors(@Nullable ChannelInterceptor... interceptors) {
        if (interceptors != null) {
            this.interceptors.addAll(Arrays.asList(interceptors));
        }
        return this;
    }

}
